What is this hole for?

Pulled the engine/transmission, 1969 MGB, single handedly, and I was surprised how easy the job turned out to be. I'll get a second pair of hands when I re-install it in the repainted engine bay, though.
My question--There is a hole in the rear engine plate below the starter hole which contained a rotted rubber plug. When I removed the plug, it crumbled into pieces. The plug appeared to have been inserted from the rear of the engine plate. What was this hole placed there for? Some reason to access the flywheel face? Moss and VB catalogs do not show any replacement plug available and in fact, their catalogs don't even show this hole on their drawings of the rear engine plate. Is there any reason to keep this hole patent (accessible), or if no replacement plug is to be found, should I just cut a steel disc and weld it into the hole, grind it flush and paint over it?
The Haynes repair manual shows a picture of the plate with a rubber plug installed, but makes no mention of it in the text.
I tried to attach 2 photos showing the hole and the remnants of the plug, but they were not accepted.

Its a flywheel breather.

Well, that was my best guess....I have no idea. My MGB has the same hole...No plug.
I did not know there was ever a plug for it....

I would be interested to know as well.


Brett

that hole was to access the torque convertor bolts on an MGB with auto trans

I bought one from a UK supplier as MGOC's PN 12H541. (Backplate Blanking Plug)

I believe Moss's replacement is the PN 297-495 (Gearbox Mountplate Cover)

Thanks, guys. My question answered, but I'll try again to attach these (reduced size) photos.

"I believe Moss's replacement is the PN 297-495 (Gearbox Mountplate Cover)"

That's it.

That actually looks more substantial and engineered than what came out of mine John.
Is there a metal disk in yours? Mine just had a slimy rubber plug in it. (And the new one is just a dry and clean rubber plug)

Discusion relating to this from January 2007:

http://www.mgexperience.net/archive/automatic_mgb/501686

John,, you have raised an interesting question. Can this hole be permanently sealed over without any detrimental effects on the flywheel/clutch assembly. It would seem to me that any 'breathing' could be accomplished via the shifter fork boot just as easily. Has anyone welded in a plug lieu of the rubber ones that are currently available and subject to disintegrate again over time?

Other backplates do not have the hole, so it is unnecessary for the functioning of the flywheel. Makes the car lighter though!

GERONIMO Wrote:

Personally, I wouldn't sweat it. The flywheel spinning around will keep it clear of anything that makes it up there...

OTOH a chunk of gravel could be pretty interesting!

Changed my mind. You could get a blanking plate at the local parts supply house... you know, the chrome thingy with "fingers."

And here is a photo of the inside of a bellhousing where this plug had gone missing for quite a long time. It needs to be there, especially if your engine leaks, front or rear. That oil mist and god only knows what else will find shelter inside your bell housing.

The crap you see was a mixture of oil and graphite and grit ~ very likely road grit. Neither the input shaft or rear main seals were leaking, nor the gasket for the input shaft nose housing. The accumulation was thick enough to have probably taken quite a while to have gotten that way. FWIW

Nice t/o bearing. Why is the tranny out? ;)

If you are asking me, it was out to replace the T/O bearing, and the rest of the clutch after 75K miles and 17 yrs of daily use. When taken apart, a broken pressure plate (2 broken fingers) was also revealed, besides the exploded T/O bearing. I doubt that the pressure plate was affected too much by the crap that got inside, probably for the reason you mentioned above, but there was plenty of opportunity for the T/O to be affected by the crap that came through the hole.

I don't ride the clutch and never have with this car. I learned a long time ago not to. But I must admit that I had not noticed that the plug had fallen out of the hole since it normally sits behind the backside of the pan ~ out of sight, out of mind. When you don't have much need to be working in that area, it is not too hard to miss it, I guess. But there is no need for anyone else to make the same mistake.

for the $8.90 cost I would just get the moss plug to blank it.
if that's too uch for you then perhaps an aerial blanking plate form any auto parts store may fit. I am not sure of the diameter of the hole